1. Field of the Invention
The invention relates to a drilling system for drilling a borehole in the earth with a directional control system.
2. Description of the Prior Art
In recent history, the utility industry has been using methods of placing conduits and cable in the ground without forming trenches. This is known as trenchless technology and is carried out by drilling, using machines that advance a drill string into the ground and guiding it around obstacles to the exit point desired. There is no problem in drilling in dirt using techniques and equipment similar to those found in U.S. Pat. No. 4,953,638. Also the oil and gas drilling systems have for many years used devices to direct a drill stem to desired locations. These systems use devices such as whipstocks and downhole motors mounted on bent shafts. When the drilling system, used by the utility industry, encounters rock, the operators have used downhole motors and devices that use two stems, one for cutting and one for steering such as disclosed in U.S. Pat. No. 5,490,569. It requires a special machine to operate these systems and the cost of such machines is very high. Moreover the downhole motors that use water, require environmental clean up which present problems. Other prior art drilling systems are disclosed in U.S. Pat. Nos. 4,281,723, and 5,423,388.